“…This so called HP model [84] has been extensively studied by Chan and Dill [85 -94], Sali and coworkers [95 -97], Shakhnovich and coworkers [27], Karplus and coworkers [21,96,97] and many others [24,98 -106]. Modifications of this model include different codes for sequence [23,95,107 -121] (from a simple collapsing homopolymer to full twenty-residue types of sequences [117,122]), more complex (and more realistic) interaction schemes [23,25,114,116,118,[122][123][124][125][126][127][128] effects of other molecules [66,90,[129][130][131][132][133][134][135] a simple lattice representation of the side chains [62,128,133,136 -140], and modifications of the geometry of the HP model [98,141,142]. An excellent review of earlier studies of this model can be found in work of Dill et al [20].…”